Submersible pump.

[Bogart]

Was not sure if this is the correct forum but here goes. I have a well, approx 45ft deep, at the bottom of which is a submersible pump. Was originally installed to run a sprinkler system for which it was fine. Now my wife wants to use the water for general garden spraying using a hand held spray. The problem is she switches the pump on then walks to the spray before using it. In the meantime whilst she is walking to the spray the pump is banging away against a dead head, as it will every time she releases the trigger on the spray gun. I have fuffed about with a flow switch on the pipe outlet to fire up the pump only when there is a demand but it is a chicken and egg scenario. No flow = no signal from flow switch= pump does not switch on. What I need is a pump like I have on the central heating , Grundfos, where if there is no flow ie trvs shut the pump just runs ever so slowly until a trv opens then it speeds up. Any idea?

 

[rpm]

Tell her to walk quicker!

 

[fixitflav]

Was not sure if this is the correct forum but here goes. I have a well, approx 45ft deep, at the bottom of which is a submersible pump. Was originally installed to run a sprinkler system for which it was fine. Now my wife wants to use the water for general garden spraying using a hand held spray. The problem is she switches the pump on then walks to the spray before using it. In the meantime whilst she is walking to the spray the pump is banging away against a dead head, as it will every time she releases the trigger on the spray gun. I have fuffed about with a flow switch on the pipe outlet to fire up the pump only when there is a demand but it is a chicken and egg scenario. No flow = no signal from flow switch= pump does not switch on. What I need is a pump like I have on the central heating , Grundfos, where if there is no flow ie trvs shut the pump just runs ever so slowly until a trv opens then it speeds up. Any idea?

I don't think there'll be a problem. Centrifugal pumps can run against a closed valve for a while. Hydropneumatic booster sets often have a minimum run timer, to limit pump start frequency, rather than using a bigger air vessel. If maximum allowed start frequency is say 10 per hour, the timer is set to 6 minutes. If demand stops in that time it continues to run, and it works OK. Also as the pump is submerged the heat is dissipated well. And at closed valve it probably draws less electrical power than when pumping.
You could always ask the pump supplier what he thinks.

 

[ShaunCorbs]

Can't you wire a flow switch inline to the pump ?

Or have a bypass eg water goes somewhere

 

[rpm]

Don't see why people are making something simple complicated.
Also has anyone read previous thread?

 

[skoronesa]

You guys dont have many submersible pumps over there do you? You just need a well tank and a pressure switch. Maybe a check valve too if the pump doesnt have one built in.

From pump to check valve then tee for tank and a tapping for the pressure switch then off to your hose spigot. The pressure switch will connect when the pressure is low. The pump runs until the pressure gets high enough to trip the switch off. This should last for at least 45 seconds, preferrably a minute. Then as your wife waters the pressure drops as the tank empties and the switch kicks on again.

The tank will probably need to be around 25gallons. Set the air pressure in the tank to just shy of the switch cut in pressure before you start the pump for the first time.

Modern well tanks have a rubber bladder for the water but a simple tank works too, you'll just have to empty some water and add air every once in a while.

 

[skoronesa]

A pressure relief valve set below the max pressure of your components would be good too.

 

[Bogart]

You guys dont have many submersible pumps over there do you? You just need a well tank and a pressure switch. Maybe a check valve too if the pump doesnt have one built in.

Trying to keep it simple so adding another tank is out.

 

[Bogart]

Can't you wire a flow switch inline to the pump ?

Or have a bypass eg water goes somewhere

That is what I did but it cannot switch the pump on till water flows and water will not flow until the pump is on. Am thinking along same lines as yourself and just having a tee off that just goes back into the well.

 

[chris watkins]

It sounds like you just need to install a differential pressure switch to control the bore hole pump. They are are less than £50 just need to know what the pump head is.

 

[skoronesa]

That is what I did but it cannot switch the pump on till water flows and water will not flow until the pump is on. Am thinking along same lines as yourself and just having a tee off that just goes back into the well.

So get a pressure relief valve and pipe the discharge back into the well. When you use the garden hose the pressure will drop and the relief will close and the only water coming out will be from the hose.

Mind you this is probably going to work the pump really hard.

 

[fixitflav]

You guys dont have many submersible pumps over there do you? You just need a well tank and a pressure switch. Maybe a check valve too if the pump doesnt have one built in.

From pump to check valve then tee for tank and a tapping for the pressure switch then off to your hose spigot. The pressure switch will connect when the pressure is low. The pump runs until the pressure gets high enough to trip the switch off. This should last for at least 45 seconds, preferrably a minute. Then as your wife waters the pressure drops as the tank empties and the switch kicks on again.

The tank will probably need to be around 25gallons. Set the air pressure in the tank to just shy of the switch cut in pressure before you start the pump for the first time.

Modern well tanks have a rubber bladder for the water but a simple tank works too, you'll just have to empty some water and add air every once in a while.

We do have submersible pumps over here, and we have hydropneumatic sets as well. BTW, hydropneumatic don’t have just submersible pumps.

For a well supplying all a house’s needs, at any time, a vessel and pressure switch would be all but indispensable, but that’s not the situation here. The OP just wants to start the pump manually when required, and he has confirmed in #8, he doesn’t want to go to the trouble and expense of what you describe. And as I said in #3, I don’t think it’s necessary.

I don’t know how you get 25 gals (US assumed), but that seems oversized. Assuming the water in/out between pump start/stop is ½ that (obviously more details about the application needed to work it out accurately) and maximum 20 starts/h, that’s enough for a pump output over 16 USgpm. For a ½” hose he probably only needs ~ 5 USgpm. In any case, it’s normal to use a smaller vessel than calculated from start frequency, and limit starts by a minimum run timer, as I said in #3.

 

[fixitflav]

A pressure relief valve set below the max pressure of your components would be good too.

Unlikely to be necessary if the closed-valve pump pressure is below what the kit can take, as it probably will be.

 

[rpm]

The OP just wants to start the pump manually when required.

Exactly !!!
So you have a water supply, an electrical supply, a pump, a (hopefully) fixed metal pipe to the surface then a hose with a gun.
Strip out any flow valve and control it with a "X".

X is staring you all in the face.
KISS (Keep it simple stupid!)

 

[Bogart]

Exactly !!!
So you have a water supply, an electrical supply, a pump, a (hopefully) fixed metal pipe to the surface then a hose with a gun.
Strip out any flow valve and control it with a "X".

X is staring you all in the face.
KISS (Keep it simple stupid!)

Well, forgive the pun, X is not staring ME in the face. Oh and it is 32mm MDPE pipe coming from the pump.

 

[rpm]

What pump is it?

 

[Bogart]

Do not know as not lifted up and it could be awkward if it is mdpe all the way down.

 

[rpm]

Should be on a chain.
Whilst you're here how is it wired up?

 

[skoronesa]

So have you gotten it working yet?

 

[rpm]

So have you gotten it working yet?

 

[fixitflav]

So have you gotten it working yet?

That's not the issue. It's already working, he wants to know whether it's OK to run it like his wife wants to.

 

[skoronesa]

I thought the issue was that he had it hooked up so when she was using it and stopped spraying the pump was deadheaded until she got to turn off the pump. Or he had a flow switch but it wasn't working right.

 

[Bogart]

The former. I tried the flow switch setup but it did not work. Will try to get the pump out over the weekend to just at least have a look at it.

 

[fixitflav]

I thought the issue was that he had it hooked up so when she was using it and stopped spraying the pump was deadheaded until she got to turn off the pump. Or he had a flow switch but it wasn't working right.

Yes, you're right, I take that back. Reading the original post again, he's still trying to prevent it, not considering whether or not it's a problem. As I said, I don't think it is, for the minute or 2 to get from starting the pump to opening the spray trigger.
For a flow switch to work, need a timer in parallel with the flow switch, set to a bit longer than it takes to get from the start button to the trigger. So the timer starts, the timer contacts close and the pump runs. If the flow switch contacts close before the timer contacts open, the pump keeps running. If not, the pump stops when the timer expires. Downside is the pump stops when the trigger is released (unless more features added to the circuit). Seems a lot of trouble for something this simple. Maybe a module is available off the shelf.

 

[Bogart]

Yes could get complicated regarding adding this or that to overcome one problem or another. Also though the walk from the well to the spray head at most will be 30 seconds approximately I cannot guarantee she will not stop spraying, shut the spraygun off then disappear off somewhere else before remembering to go and switch of the pump.